Fix macOS date command and add environment variable validation

Co-authored-by: larsdecker <1968186+larsdecker@users.noreply.github.com>

Author: Copilot

packages/fints-cli/README.md

@@ -285,7 +285,7 @@ END_DATE=$(date -d "-1 day $(date +%Y-%m-01)" +%Y-%m-%d)
 
 # For macOS (BSD date), use:
 # START_DATE=$(date -v-1m +%Y-%m-01)
-# END_DATE=$(date -v-1d -v1d +%Y-%m-%d)
+# END_DATE=$(date -v1d -v-1m -v-1d +%Y-%m-%d)
 # Or install GNU coreutils (brew install coreutils) and use 'gdate'
 
 # Fetch transactions

packages/fints/README.md

@@ -286,11 +286,17 @@ for (const account of accounts) {
 import { PinTanClient } from "fints-lib";
 
 // Create client using environment variables for credentials
+// Ensure environment variables are set before running
+if (!process.env.FINTS_URL || !process.env.FINTS_USERNAME || 
+    !process.env.FINTS_PIN || !process.env.FINTS_BLZ) {
+    throw new Error("Required environment variables are not set");
+}
+
 const client = new PinTanClient({
-    url: process.env.FINTS_URL!,
-    name: process.env.FINTS_USERNAME!,
-    pin: process.env.FINTS_PIN!,
-    blz: process.env.FINTS_BLZ!,
+    url: process.env.FINTS_URL,
+    name: process.env.FINTS_USERNAME,
+    pin: process.env.FINTS_PIN,
+    blz: process.env.FINTS_BLZ,
     debug: process.env.NODE_ENV === "development",
 });